초록
<P><B>Abstract</B></P> <P>This study reported an environment friendly process for xylitol bioconversion from corncob hemicellulose hydrolysate prepared through xylanolytic enzymes by adapted <I>Candida tropicalis</I>. In order to improve the production of xylanolytic enzymes from <I>Aspergillus terreus</I>, the fermentation medium and growth conditions were optimized. Maximum xylanase (722U/g) and β-xylosidase (196U/g) production were exhibited on wheat bran and corncob (mass ratio of 7:3) medium supplemented with 2% (v/v) NaNO<SUB>3</SUB> and 0.05% (v/v) Tween 80 at pH 6.8, 1:1 (v/w) moisture level, 20% inoculum level and 30°C for 120h of cultivation. For preparation of corncob hemicellulose hydrolysate, the optimum enzymatic hydrolysis conditions contained enzyme dosage (30.6U/g), water addition (19.2mL/g), temperature (48.01°C), pH (5.75). Under these conditions, the sugars of 18.03g/L xylose and 4.87g/L glucose were obtained in 8h. The corncob hemicellulose hydrolysate was used for xylitol fermentation and the maximum xylitol yield of 75.14% was obtained by adapted <I>C. tropicalis</I> after the optimization of fermentation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A green process was developed for hydrolysate preparation and xylitol production. </LI> <LI> Different conditions were investigated to improve xylanolytic enzymes production. </LI> <LI> Different parameters were optimized to prepare corncob hemicellulose hydrolysate. </LI> <LI> High xylitol yield was obtained from hydrolysate by adapted <I>Candida tropicalis</I>. </LI> </UL> </P>